Why doesn't the Lord grant us everything we prayed for?

Someone once posed this question to me 'why doesn't the Lord grant us everything we prayed for?' some years ago and I tried to explain but the answers given were not accepted. The argument was centered on this - that since the Father did not spare His Son but sent Jesus to die for us, how can He not give us everything? if He had already spared His most precious possession, how difficult is it for Him to grant mere men's requests?

Obvious, the confusion lies in Romans 8:26-27 and recently I read an excellent explanation of these two verses from "The Letter to the Romans - The NEW Daily Study Bible" by the late William Barclay. On page 131, he said. "Paul is saying that, because of our weakness, we do not know what to pray for, but the prayers we ought to offer are offered for us by the Hly Spirit. The New Testament scholar C.H. Dodd defines prayer in this way: 'Prayer is the divine in us appealing to the Divine above us.'"

In his book, he explained that there are two very obvious reasons why we cannot pray as we ought. We cannot pray aright because
1. we cannot foresee the future. We cannot see a year or even an hour ahead; and we may well pray, therefore, to be saved from things which are for our good, and we may pray for things which would be to our ultimate harm.
2. in any given situation we do not know what is best for us. We are often in the position of children who want something which would be bound only to hurt them; and God is often in the position of parents who have to refuse their children's requests or compel them to do something they do not want to do, because the parents know what is good for them far better than the children themselves.

Wow, when I read that I was relieved because that is exactly how things should be. To his readers who argued with him, Paul wrote in Romans 9:20-21,
v20 But who are you, O man, to talk back to God? "Shall what is formed say to him who formed it, 'Why did you make me like this?'"
v21 Does not the potter have the right to make out of the same lump of clay some pottery for noble purposes and some for common use?

So the moral of the story - the Lord wants us to have the best and He will not short-change His children. So go ahead and give thanks for whatever He gives us.